xref: /openbmc/linux/sound/drivers/serial-u16550.c (revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2)
1 /*
2  *   serial.c
3  *   Copyright (c) by Jaroslav Kysela <perex@suse.cz>,
4  *                    Isaku Yamahata <yamahata@private.email.ne.jp>,
5  *		      George Hansper <ghansper@apana.org.au>,
6  *		      Hannu Savolainen
7  *
8  *   This code is based on the code from ALSA 0.5.9, but heavily rewritten.
9  *
10  *   This program is free software; you can redistribute it and/or modify
11  *   it under the terms of the GNU General Public License as published by
12  *   the Free Software Foundation; either version 2 of the License, or
13  *   (at your option) any later version.
14  *
15  *   This program is distributed in the hope that it will be useful,
16  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
17  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18  *   GNU General Public License for more details.
19  *
20  *   You should have received a copy of the GNU General Public License
21  *   along with this program; if not, write to the Free Software
22  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
23  *
24  * Sat Mar 31 17:27:57 PST 2001 tim.mann@compaq.com
25  *      Added support for the Midiator MS-124T and for the MS-124W in
26  *      Single Addressed (S/A) or Multiple Burst (M/B) mode, with
27  *      power derived either parasitically from the serial port or
28  *      from a separate power supply.
29  *
30  *      More documentation can be found in serial-u16550.txt.
31  */
32 
33 #include <sound/driver.h>
34 #include <linux/init.h>
35 #include <linux/interrupt.h>
36 #include <linux/slab.h>
37 #include <linux/ioport.h>
38 #include <linux/moduleparam.h>
39 #include <sound/core.h>
40 #include <sound/rawmidi.h>
41 #include <sound/initval.h>
42 
43 #include <linux/serial_reg.h>
44 
45 #include <asm/io.h>
46 
47 MODULE_DESCRIPTION("MIDI serial u16550");
48 MODULE_LICENSE("GPL");
49 MODULE_SUPPORTED_DEVICE("{{ALSA, MIDI serial u16550}}");
50 
51 #define SNDRV_SERIAL_SOUNDCANVAS 0 /* Roland Soundcanvas; F5 NN selects part */
52 #define SNDRV_SERIAL_MS124T 1      /* Midiator MS-124T */
53 #define SNDRV_SERIAL_MS124W_SA 2   /* Midiator MS-124W in S/A mode */
54 #define SNDRV_SERIAL_MS124W_MB 3   /* Midiator MS-124W in M/B mode */
55 #define SNDRV_SERIAL_GENERIC 4     /* Generic Interface */
56 #define SNDRV_SERIAL_MAX_ADAPTOR SNDRV_SERIAL_GENERIC
57 static char *adaptor_names[] = {
58 	"Soundcanvas",
59         "MS-124T",
60 	"MS-124W S/A",
61 	"MS-124W M/B",
62 	"Generic"
63 };
64 
65 #define SNDRV_SERIAL_NORMALBUFF 0 /* Normal blocking buffer operation */
66 #define SNDRV_SERIAL_DROPBUFF   1 /* Non-blocking discard operation */
67 
68 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;	/* Index 0-MAX */
69 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;	/* ID for this card */
70 static int enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE; /* Enable this card */
71 static long port[SNDRV_CARDS] = SNDRV_DEFAULT_PORT; /* 0x3f8,0x2f8,0x3e8,0x2e8 */
72 static int irq[SNDRV_CARDS] = SNDRV_DEFAULT_IRQ; 	/* 3,4,5,7,9,10,11,14,15 */
73 static int speed[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 38400}; /* 9600,19200,38400,57600,115200 */
74 static int base[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 115200}; /* baud base */
75 static int outs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};	 /* 1 to 16 */
76 static int ins[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};	/* 1 to 16 */
77 static int adaptor[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = SNDRV_SERIAL_SOUNDCANVAS};
78 static int droponfull[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS -1)] = SNDRV_SERIAL_NORMALBUFF };
79 
80 module_param_array(index, int, NULL, 0444);
81 MODULE_PARM_DESC(index, "Index value for Serial MIDI.");
82 module_param_array(id, charp, NULL, 0444);
83 MODULE_PARM_DESC(id, "ID string for Serial MIDI.");
84 module_param_array(enable, bool, NULL, 0444);
85 MODULE_PARM_DESC(enable, "Enable UART16550A chip.");
86 module_param_array(port, long, NULL, 0444);
87 MODULE_PARM_DESC(port, "Port # for UART16550A chip.");
88 module_param_array(irq, int, NULL, 0444);
89 MODULE_PARM_DESC(irq, "IRQ # for UART16550A chip.");
90 module_param_array(speed, int, NULL, 0444);
91 MODULE_PARM_DESC(speed, "Speed in bauds.");
92 module_param_array(base, int, NULL, 0444);
93 MODULE_PARM_DESC(base, "Base for divisor in bauds.");
94 module_param_array(outs, int, NULL, 0444);
95 MODULE_PARM_DESC(outs, "Number of MIDI outputs.");
96 module_param_array(ins, int, NULL, 0444);
97 MODULE_PARM_DESC(ins, "Number of MIDI inputs.");
98 module_param_array(droponfull, bool, NULL, 0444);
99 MODULE_PARM_DESC(droponfull, "Flag to enable drop-on-full buffer mode");
100 
101 module_param_array(adaptor, int, NULL, 0444);
102 MODULE_PARM_DESC(adaptor, "Type of adaptor.");
103 
104 /*#define SNDRV_SERIAL_MS124W_MB_NOCOMBO 1*/  /* Address outs as 0-3 instead of bitmap */
105 
106 #define SNDRV_SERIAL_MAX_OUTS	16		/* max 64, min 16 */
107 #define SNDRV_SERIAL_MAX_INS	16		/* max 64, min 16 */
108 
109 #define TX_BUFF_SIZE		(1<<15)		/* Must be 2^n */
110 #define TX_BUFF_MASK		(TX_BUFF_SIZE - 1)
111 
112 #define SERIAL_MODE_NOT_OPENED 		(0)
113 #define SERIAL_MODE_INPUT_OPEN		(1 << 0)
114 #define SERIAL_MODE_OUTPUT_OPEN		(1 << 1)
115 #define SERIAL_MODE_INPUT_TRIGGERED	(1 << 2)
116 #define SERIAL_MODE_OUTPUT_TRIGGERED	(1 << 3)
117 
118 typedef struct _snd_uart16550 {
119 	snd_card_t *card;
120 	snd_rawmidi_t *rmidi;
121 	snd_rawmidi_substream_t *midi_output[SNDRV_SERIAL_MAX_OUTS];
122 	snd_rawmidi_substream_t *midi_input[SNDRV_SERIAL_MAX_INS];
123 
124 	int filemode;		//open status of file
125 
126 	spinlock_t open_lock;
127 
128 	int irq;
129 
130 	unsigned long base;
131 	struct resource *res_base;
132 
133 	unsigned int speed;
134 	unsigned int speed_base;
135 	unsigned char divisor;
136 
137 	unsigned char old_divisor_lsb;
138 	unsigned char old_divisor_msb;
139 	unsigned char old_line_ctrl_reg;
140 
141 	// parameter for using of write loop
142 	short int fifo_limit;	//used in uart16550
143         short int fifo_count;	//used in uart16550
144 
145 	// type of adaptor
146 	int adaptor;
147 
148 	// inputs
149 	int prev_in;
150 	unsigned char rstatus;
151 
152 	// outputs
153 	int prev_out;
154 	unsigned char prev_status[SNDRV_SERIAL_MAX_OUTS];
155 
156 	// write buffer and its writing/reading position
157 	unsigned char tx_buff[TX_BUFF_SIZE];
158 	int buff_in_count;
159         int buff_in;
160         int buff_out;
161         int drop_on_full;
162 
163 	// wait timer
164 	unsigned int timer_running:1;
165 	struct timer_list buffer_timer;
166 
167 } snd_uart16550_t;
168 
169 static snd_card_t *snd_serial_cards[SNDRV_CARDS] = SNDRV_DEFAULT_PTR;
170 
171 inline static void snd_uart16550_add_timer(snd_uart16550_t *uart)
172 {
173 	if (! uart->timer_running) {
174 		/* timer 38600bps * 10bit * 16byte */
175 		uart->buffer_timer.expires = jiffies + (HZ+255)/256;
176 		uart->timer_running = 1;
177 		add_timer(&uart->buffer_timer);
178 	}
179 }
180 
181 inline static void snd_uart16550_del_timer(snd_uart16550_t *uart)
182 {
183 	if (uart->timer_running) {
184 		del_timer(&uart->buffer_timer);
185 		uart->timer_running = 0;
186 	}
187 }
188 
189 /* This macro is only used in snd_uart16550_io_loop */
190 inline static void snd_uart16550_buffer_output(snd_uart16550_t *uart)
191 {
192 	unsigned short buff_out = uart->buff_out;
193 	if( uart->buff_in_count > 0 ) {
194 		outb(uart->tx_buff[buff_out], uart->base + UART_TX);
195 		uart->fifo_count++;
196 		buff_out++;
197 		buff_out &= TX_BUFF_MASK;
198 		uart->buff_out = buff_out;
199 		uart->buff_in_count--;
200 	}
201 }
202 
203 /* This loop should be called with interrupts disabled
204  * We don't want to interrupt this,
205  * as we're already handling an interrupt
206  */
207 static void snd_uart16550_io_loop(snd_uart16550_t * uart)
208 {
209 	unsigned char c, status;
210 	int substream;
211 
212 	/* recall previous stream */
213 	substream = uart->prev_in;
214 
215 	/* Read Loop */
216 	while ((status = inb(uart->base + UART_LSR)) & UART_LSR_DR) {
217 		/* while receive data ready */
218 		c = inb(uart->base + UART_RX);
219 
220 		/* keep track of last status byte */
221 		if (c & 0x80) {
222 			uart->rstatus = c;
223 		}
224 
225 		/* handle stream switch */
226 		if (uart->adaptor == SNDRV_SERIAL_GENERIC) {
227 			if (uart->rstatus == 0xf5) {
228 				if (c <= SNDRV_SERIAL_MAX_INS && c > 0)
229 					substream = c - 1;
230 				if (c != 0xf5)
231 					uart->rstatus = 0; /* prevent future bytes from being interpreted as streams */
232 			}
233 			else if ((uart->filemode & SERIAL_MODE_INPUT_OPEN) && (uart->midi_input[substream] != NULL)) {
234 				snd_rawmidi_receive(uart->midi_input[substream], &c, 1);
235 			}
236 		} else if ((uart->filemode & SERIAL_MODE_INPUT_OPEN) && (uart->midi_input[substream] != NULL)) {
237 			snd_rawmidi_receive(uart->midi_input[substream], &c, 1);
238 		}
239 
240 		if (status & UART_LSR_OE)
241 			snd_printk("%s: Overrun on device at 0x%lx\n",
242 			       uart->rmidi->name, uart->base);
243 	}
244 
245 	/* remember the last stream */
246 	uart->prev_in = substream;
247 
248 	/* no need of check SERIAL_MODE_OUTPUT_OPEN because if not,
249 	   buffer is never filled. */
250 	/* Check write status */
251 	if (status & UART_LSR_THRE) {
252 		uart->fifo_count = 0;
253 	}
254 	if (uart->adaptor == SNDRV_SERIAL_MS124W_SA
255 	   || uart->adaptor == SNDRV_SERIAL_GENERIC) {
256 		/* Can't use FIFO, must send only when CTS is true */
257 		status = inb(uart->base + UART_MSR);
258 		while( (uart->fifo_count == 0) && (status & UART_MSR_CTS) &&
259 		      (uart->buff_in_count > 0) ) {
260 		       snd_uart16550_buffer_output(uart);
261 		       status = inb( uart->base + UART_MSR );
262 		}
263 	} else {
264 		/* Write loop */
265 		while (uart->fifo_count < uart->fifo_limit	/* Can we write ? */
266 		       && uart->buff_in_count > 0)	/* Do we want to? */
267 			snd_uart16550_buffer_output(uart);
268 	}
269 	if (uart->irq < 0 && uart->buff_in_count > 0)
270 		snd_uart16550_add_timer(uart);
271 }
272 
273 /* NOTES ON SERVICING INTERUPTS
274  * ---------------------------
275  * After receiving a interrupt, it is important to indicate to the UART that
276  * this has been done.
277  * For a Rx interrupt, this is done by reading the received byte.
278  * For a Tx interrupt this is done by either:
279  * a) Writing a byte
280  * b) Reading the IIR
281  * It is particularly important to read the IIR if a Tx interrupt is received
282  * when there is no data in tx_buff[], as in this case there no other
283  * indication that the interrupt has been serviced, and it remains outstanding
284  * indefinitely. This has the curious side effect that and no further interrupts
285  * will be generated from this device AT ALL!!.
286  * It is also desirable to clear outstanding interrupts when the device is
287  * opened/closed.
288  *
289  *
290  * Note that some devices need OUT2 to be set before they will generate
291  * interrupts at all. (Possibly tied to an internal pull-up on CTS?)
292  */
293 static irqreturn_t snd_uart16550_interrupt(int irq, void *dev_id, struct pt_regs *regs)
294 {
295 	snd_uart16550_t *uart;
296 
297 	uart = (snd_uart16550_t *) dev_id;
298 	spin_lock(&uart->open_lock);
299 	if (uart->filemode == SERIAL_MODE_NOT_OPENED) {
300 		spin_unlock(&uart->open_lock);
301 		return IRQ_NONE;
302 	}
303 	inb(uart->base + UART_IIR);		/* indicate to the UART that the interrupt has been serviced */
304 	snd_uart16550_io_loop(uart);
305 	spin_unlock(&uart->open_lock);
306 	return IRQ_HANDLED;
307 }
308 
309 /* When the polling mode, this function calls snd_uart16550_io_loop. */
310 static void snd_uart16550_buffer_timer(unsigned long data)
311 {
312 	unsigned long flags;
313 	snd_uart16550_t *uart;
314 
315 	uart = (snd_uart16550_t *)data;
316 	spin_lock_irqsave(&uart->open_lock, flags);
317 	snd_uart16550_del_timer(uart);
318 	snd_uart16550_io_loop(uart);
319 	spin_unlock_irqrestore(&uart->open_lock, flags);
320 }
321 
322 /*
323  *  this method probes, if an uart sits on given port
324  *  return 0 if found
325  *  return negative error if not found
326  */
327 static int __init snd_uart16550_detect(snd_uart16550_t *uart)
328 {
329 	unsigned long io_base = uart->base;
330 	int ok;
331 	unsigned char c;
332 
333 	/* Do some vague tests for the presence of the uart */
334 	if (io_base == 0 || io_base == SNDRV_AUTO_PORT) {
335 		return -ENODEV;	/* Not configured */
336 	}
337 
338 	uart->res_base = request_region(io_base, 8, "Serial MIDI");
339 	if (uart->res_base == NULL) {
340 		snd_printk(KERN_ERR "u16550: can't grab port 0x%lx\n", io_base);
341 		return -EBUSY;
342 	}
343 
344 	ok = 1;			/* uart detected unless one of the following tests should fail */
345 	/* 8 data-bits, 1 stop-bit, parity off, DLAB = 0 */
346 	outb(UART_LCR_WLEN8, io_base + UART_LCR); /* Line Control Register */
347 	c = inb(io_base + UART_IER);
348 	/* The top four bits of the IER should always == 0 */
349 	if ((c & 0xf0) != 0)
350 		ok = 0;		/* failed */
351 
352 	outb(0xaa, io_base + UART_SCR);
353 	/* Write arbitrary data into the scratch reg */
354 	c = inb(io_base + UART_SCR);
355 	/* If it comes back, it's OK */
356 	if (c != 0xaa)
357 		ok = 0;		/* failed */
358 
359 	outb(0x55, io_base + UART_SCR);
360 	/* Write arbitrary data into the scratch reg */
361 	c = inb(io_base + UART_SCR);
362 	/* If it comes back, it's OK */
363 	if (c != 0x55)
364 		ok = 0;		/* failed */
365 
366 	return ok;
367 }
368 
369 static void snd_uart16550_do_open(snd_uart16550_t * uart)
370 {
371 	char byte;
372 
373 	/* Initialize basic variables */
374 	uart->buff_in_count = 0;
375 	uart->buff_in = 0;
376 	uart->buff_out = 0;
377 	uart->fifo_limit = 1;
378 	uart->fifo_count = 0;
379 	uart->timer_running = 0;
380 
381 	outb(UART_FCR_ENABLE_FIFO	/* Enable FIFO's (if available) */
382 	     | UART_FCR_CLEAR_RCVR	/* Clear receiver FIFO */
383 	     | UART_FCR_CLEAR_XMIT	/* Clear transmitter FIFO */
384 	     | UART_FCR_TRIGGER_4	/* Set FIFO trigger at 4-bytes */
385 	/* NOTE: interrupt generated after T=(time)4-bytes
386 	 * if less than UART_FCR_TRIGGER bytes received
387 	 */
388 	     ,uart->base + UART_FCR);	/* FIFO Control Register */
389 
390 	if ((inb(uart->base + UART_IIR) & 0xf0) == 0xc0)
391 		uart->fifo_limit = 16;
392 	if (uart->divisor != 0) {
393 		uart->old_line_ctrl_reg = inb(uart->base + UART_LCR);
394 		outb(UART_LCR_DLAB	/* Divisor latch access bit */
395 		     ,uart->base + UART_LCR);	/* Line Control Register */
396 		uart->old_divisor_lsb = inb(uart->base + UART_DLL);
397 		uart->old_divisor_msb = inb(uart->base + UART_DLM);
398 
399 		outb(uart->divisor
400 		     ,uart->base + UART_DLL);	/* Divisor Latch Low */
401 		outb(0
402 		     ,uart->base + UART_DLM);	/* Divisor Latch High */
403 		/* DLAB is reset to 0 in next outb() */
404 	}
405 	/* Set serial parameters (parity off, etc) */
406 	outb(UART_LCR_WLEN8	/* 8 data-bits */
407 	     | 0		/* 1 stop-bit */
408 	     | 0		/* parity off */
409 	     | 0		/* DLAB = 0 */
410 	     ,uart->base + UART_LCR);	/* Line Control Register */
411 
412 	switch (uart->adaptor) {
413 	default:
414 		outb(UART_MCR_RTS	/* Set Request-To-Send line active */
415 		     | UART_MCR_DTR	/* Set Data-Terminal-Ready line active */
416 		     | UART_MCR_OUT2	/* Set OUT2 - not always required, but when
417 					 * it is, it is ESSENTIAL for enabling interrupts
418 				 */
419 		     ,uart->base + UART_MCR);	/* Modem Control Register */
420 		break;
421 	case SNDRV_SERIAL_MS124W_SA:
422 	case SNDRV_SERIAL_MS124W_MB:
423 		/* MS-124W can draw power from RTS and DTR if they
424 		   are in opposite states. */
425 		outb(UART_MCR_RTS | (0&UART_MCR_DTR) | UART_MCR_OUT2,
426 		     uart->base + UART_MCR);
427 		break;
428 	case SNDRV_SERIAL_MS124T:
429 		/* MS-124T can draw power from RTS and/or DTR (preferably
430 		   both) if they are both asserted. */
431 		outb(UART_MCR_RTS | UART_MCR_DTR | UART_MCR_OUT2,
432 		     uart->base + UART_MCR);
433 		break;
434 	}
435 
436 	if (uart->irq < 0) {
437 		byte = (0 & UART_IER_RDI)	/* Disable Receiver data interrupt */
438 		    |(0 & UART_IER_THRI)	/* Disable Transmitter holding register empty interrupt */
439 		    ;
440 	} else if (uart->adaptor == SNDRV_SERIAL_MS124W_SA) {
441 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
442 		    | UART_IER_MSI	/* Enable Modem status interrupt */
443 		    ;
444 	} else if (uart->adaptor == SNDRV_SERIAL_GENERIC) {
445 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
446 		    | UART_IER_MSI	/* Enable Modem status interrupt */
447 		    | UART_IER_THRI	/* Enable Transmitter holding register empty interrupt */
448 		    ;
449 	} else {
450 		byte = UART_IER_RDI	/* Enable Receiver data interrupt */
451 		    | UART_IER_THRI	/* Enable Transmitter holding register empty interrupt */
452 		    ;
453 	}
454 	outb(byte, uart->base + UART_IER);	/* Interupt enable Register */
455 
456 	inb(uart->base + UART_LSR);	/* Clear any pre-existing overrun indication */
457 	inb(uart->base + UART_IIR);	/* Clear any pre-existing transmit interrupt */
458 	inb(uart->base + UART_RX);	/* Clear any pre-existing receive interrupt */
459 }
460 
461 static void snd_uart16550_do_close(snd_uart16550_t * uart)
462 {
463 	if (uart->irq < 0)
464 		snd_uart16550_del_timer(uart);
465 
466 	/* NOTE: may need to disable interrupts before de-registering out handler.
467 	 * For now, the consequences are harmless.
468 	 */
469 
470 	outb((0 & UART_IER_RDI)		/* Disable Receiver data interrupt */
471 	     |(0 & UART_IER_THRI)	/* Disable Transmitter holding register empty interrupt */
472 	     ,uart->base + UART_IER);	/* Interupt enable Register */
473 
474 	switch (uart->adaptor) {
475 	default:
476 		outb((0 & UART_MCR_RTS)		/* Deactivate Request-To-Send line  */
477 		     |(0 & UART_MCR_DTR)	/* Deactivate Data-Terminal-Ready line */
478 		     |(0 & UART_MCR_OUT2)	/* Deactivate OUT2 */
479 		     ,uart->base + UART_MCR);	/* Modem Control Register */
480 	  break;
481 	case SNDRV_SERIAL_MS124W_SA:
482 	case SNDRV_SERIAL_MS124W_MB:
483 		/* MS-124W can draw power from RTS and DTR if they
484 		   are in opposite states; leave it powered. */
485 		outb(UART_MCR_RTS | (0&UART_MCR_DTR) | (0&UART_MCR_OUT2),
486 		     uart->base + UART_MCR);
487 		break;
488 	case SNDRV_SERIAL_MS124T:
489 		/* MS-124T can draw power from RTS and/or DTR (preferably
490 		   both) if they are both asserted; leave it powered. */
491 		outb(UART_MCR_RTS | UART_MCR_DTR | (0&UART_MCR_OUT2),
492 		     uart->base + UART_MCR);
493 		break;
494 	}
495 
496 	inb(uart->base + UART_IIR);	/* Clear any outstanding interrupts */
497 
498 	/* Restore old divisor */
499 	if (uart->divisor != 0) {
500 		outb(UART_LCR_DLAB		/* Divisor latch access bit */
501 		     ,uart->base + UART_LCR);	/* Line Control Register */
502 		outb(uart->old_divisor_lsb
503 		     ,uart->base + UART_DLL);	/* Divisor Latch Low */
504 		outb(uart->old_divisor_msb
505 		     ,uart->base + UART_DLM);	/* Divisor Latch High */
506 		/* Restore old LCR (data bits, stop bits, parity, DLAB) */
507 		outb(uart->old_line_ctrl_reg
508 		     ,uart->base + UART_LCR);	/* Line Control Register */
509 	}
510 }
511 
512 static int snd_uart16550_input_open(snd_rawmidi_substream_t * substream)
513 {
514 	unsigned long flags;
515 	snd_uart16550_t *uart = substream->rmidi->private_data;
516 
517 	spin_lock_irqsave(&uart->open_lock, flags);
518 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
519 		snd_uart16550_do_open(uart);
520 	uart->filemode |= SERIAL_MODE_INPUT_OPEN;
521 	uart->midi_input[substream->number] = substream;
522 	spin_unlock_irqrestore(&uart->open_lock, flags);
523 	return 0;
524 }
525 
526 static int snd_uart16550_input_close(snd_rawmidi_substream_t * substream)
527 {
528 	unsigned long flags;
529 	snd_uart16550_t *uart = substream->rmidi->private_data;
530 
531 	spin_lock_irqsave(&uart->open_lock, flags);
532 	uart->filemode &= ~SERIAL_MODE_INPUT_OPEN;
533 	uart->midi_input[substream->number] = NULL;
534 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
535 		snd_uart16550_do_close(uart);
536 	spin_unlock_irqrestore(&uart->open_lock, flags);
537 	return 0;
538 }
539 
540 static void snd_uart16550_input_trigger(snd_rawmidi_substream_t * substream, int up)
541 {
542 	unsigned long flags;
543 	snd_uart16550_t *uart = substream->rmidi->private_data;
544 
545 	spin_lock_irqsave(&uart->open_lock, flags);
546 	if (up) {
547 		uart->filemode |= SERIAL_MODE_INPUT_TRIGGERED;
548 	} else {
549 		uart->filemode &= ~SERIAL_MODE_INPUT_TRIGGERED;
550 	}
551 	spin_unlock_irqrestore(&uart->open_lock, flags);
552 }
553 
554 static int snd_uart16550_output_open(snd_rawmidi_substream_t * substream)
555 {
556 	unsigned long flags;
557 	snd_uart16550_t *uart = substream->rmidi->private_data;
558 
559 	spin_lock_irqsave(&uart->open_lock, flags);
560 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
561 		snd_uart16550_do_open(uart);
562 	uart->filemode |= SERIAL_MODE_OUTPUT_OPEN;
563 	uart->midi_output[substream->number] = substream;
564 	spin_unlock_irqrestore(&uart->open_lock, flags);
565 	return 0;
566 };
567 
568 static int snd_uart16550_output_close(snd_rawmidi_substream_t * substream)
569 {
570 	unsigned long flags;
571 	snd_uart16550_t *uart = substream->rmidi->private_data;
572 
573 	spin_lock_irqsave(&uart->open_lock, flags);
574 	uart->filemode &= ~SERIAL_MODE_OUTPUT_OPEN;
575 	uart->midi_output[substream->number] = NULL;
576 	if (uart->filemode == SERIAL_MODE_NOT_OPENED)
577 		snd_uart16550_do_close(uart);
578 	spin_unlock_irqrestore(&uart->open_lock, flags);
579 	return 0;
580 };
581 
582 inline static int snd_uart16550_buffer_can_write( snd_uart16550_t *uart, int Num )
583 {
584 	if( uart->buff_in_count + Num < TX_BUFF_SIZE )
585 		return 1;
586 	else
587 		return 0;
588 }
589 
590 inline static int snd_uart16550_write_buffer(snd_uart16550_t *uart, unsigned char byte)
591 {
592 	unsigned short buff_in = uart->buff_in;
593 	if( uart->buff_in_count < TX_BUFF_SIZE ) {
594 		uart->tx_buff[buff_in] = byte;
595 		buff_in++;
596 		buff_in &= TX_BUFF_MASK;
597 		uart->buff_in = buff_in;
598 		uart->buff_in_count++;
599 		if (uart->irq < 0) /* polling mode */
600 			snd_uart16550_add_timer(uart);
601 		return 1;
602 	} else
603 		return 0;
604 }
605 
606 static int snd_uart16550_output_byte(snd_uart16550_t *uart, snd_rawmidi_substream_t * substream, unsigned char midi_byte)
607 {
608 	if (uart->buff_in_count == 0                            /* Buffer empty? */
609 	    && ((uart->adaptor != SNDRV_SERIAL_MS124W_SA &&
610 	    uart->adaptor != SNDRV_SERIAL_GENERIC) ||
611 		(uart->fifo_count == 0                               /* FIFO empty? */
612 		 && (inb(uart->base + UART_MSR) & UART_MSR_CTS)))) { /* CTS? */
613 
614 	        /* Tx Buffer Empty - try to write immediately */
615 		if ((inb(uart->base + UART_LSR) & UART_LSR_THRE) != 0) {
616 		        /* Transmitter holding register (and Tx FIFO) empty */
617 		        uart->fifo_count = 1;
618 			outb(midi_byte, uart->base + UART_TX);
619 		} else {
620 		        if (uart->fifo_count < uart->fifo_limit) {
621 			        uart->fifo_count++;
622 				outb(midi_byte, uart->base + UART_TX);
623 			} else {
624 			        /* Cannot write (buffer empty) - put char in buffer */
625 				snd_uart16550_write_buffer(uart, midi_byte);
626 			}
627 		}
628 	} else {
629 		if( !snd_uart16550_write_buffer(uart, midi_byte) ) {
630 			snd_printk("%s: Buffer overrun on device at 0x%lx\n",
631 				   uart->rmidi->name, uart->base);
632 			return 0;
633 		}
634 	}
635 
636 	return 1;
637 }
638 
639 static void snd_uart16550_output_write(snd_rawmidi_substream_t * substream)
640 {
641 	unsigned long flags;
642 	unsigned char midi_byte, addr_byte;
643 	snd_uart16550_t *uart = substream->rmidi->private_data;
644 	char first;
645 	static unsigned long lasttime=0;
646 
647 	/* Interupts are disabled during the updating of the tx_buff,
648 	 * since it is 'bad' to have two processes updating the same
649 	 * variables (ie buff_in & buff_out)
650 	 */
651 
652 	spin_lock_irqsave(&uart->open_lock, flags);
653 
654 	if (uart->irq < 0)	//polling
655 		snd_uart16550_io_loop(uart);
656 
657 	if (uart->adaptor == SNDRV_SERIAL_MS124W_MB) {
658 		while (1) {
659 			/* buffer full? */
660 			/* in this mode we need two bytes of space */
661 			if (uart->buff_in_count > TX_BUFF_SIZE - 2)
662 				break;
663 			if (snd_rawmidi_transmit(substream, &midi_byte, 1) != 1)
664 				break;
665 #ifdef SNDRV_SERIAL_MS124W_MB_NOCOMBO
666 			/* select exactly one of the four ports */
667 			addr_byte = (1 << (substream->number + 4)) | 0x08;
668 #else
669 			/* select any combination of the four ports */
670 			addr_byte = (substream->number << 4) | 0x08;
671 			/* ...except none */
672 			if (addr_byte == 0x08) addr_byte = 0xf8;
673 #endif
674 			snd_uart16550_output_byte(uart, substream, addr_byte);
675 			/* send midi byte */
676 			snd_uart16550_output_byte(uart, substream, midi_byte);
677 		}
678 	} else {
679 		first = 0;
680 		while( 1 == snd_rawmidi_transmit_peek(substream, &midi_byte, 1) ) {
681 			/* Also send F5 after 3 seconds with no data to handle device disconnect */
682 			if (first == 0 && (uart->adaptor == SNDRV_SERIAL_SOUNDCANVAS ||
683 				uart->adaptor == SNDRV_SERIAL_GENERIC) &&
684 			   (uart->prev_out != substream->number || jiffies-lasttime > 3*HZ)) {
685 
686 				if( snd_uart16550_buffer_can_write( uart, 3 ) ) {
687 					/* Roland Soundcanvas part selection */
688 					/* If this substream of the data is different previous
689 					   substream in this uart, send the change part event */
690 					uart->prev_out = substream->number;
691 					/* change part */
692 					snd_uart16550_output_byte(uart, substream, 0xf5);
693 					/* data */
694 					snd_uart16550_output_byte(uart, substream, uart->prev_out + 1);
695 					/* If midi_byte is a data byte, send the previous status byte */
696 					if ((midi_byte < 0x80) && (uart->adaptor == SNDRV_SERIAL_SOUNDCANVAS))
697 						snd_uart16550_output_byte(uart, substream, uart->prev_status[uart->prev_out]);
698 				} else if( !uart->drop_on_full )
699 					break;
700 
701 			}
702 
703 			/* send midi byte */
704 			if( !snd_uart16550_output_byte(uart, substream, midi_byte) && !uart->drop_on_full )
705 				break;
706 
707 			if (midi_byte >= 0x80 && midi_byte < 0xf0)
708 				uart->prev_status[uart->prev_out] = midi_byte;
709 			first = 1;
710 
711 			snd_rawmidi_transmit_ack( substream, 1 );
712 		}
713 		lasttime = jiffies;
714 	}
715 	spin_unlock_irqrestore(&uart->open_lock, flags);
716 }
717 
718 static void snd_uart16550_output_trigger(snd_rawmidi_substream_t * substream, int up)
719 {
720 	unsigned long flags;
721 	snd_uart16550_t *uart = substream->rmidi->private_data;
722 
723 	spin_lock_irqsave(&uart->open_lock, flags);
724 	if (up) {
725 		uart->filemode |= SERIAL_MODE_OUTPUT_TRIGGERED;
726 	} else {
727 		uart->filemode &= ~SERIAL_MODE_OUTPUT_TRIGGERED;
728 	}
729 	spin_unlock_irqrestore(&uart->open_lock, flags);
730 	if (up)
731 		snd_uart16550_output_write(substream);
732 }
733 
734 static snd_rawmidi_ops_t snd_uart16550_output =
735 {
736 	.open =		snd_uart16550_output_open,
737 	.close =	snd_uart16550_output_close,
738 	.trigger =	snd_uart16550_output_trigger,
739 };
740 
741 static snd_rawmidi_ops_t snd_uart16550_input =
742 {
743 	.open =		snd_uart16550_input_open,
744 	.close =	snd_uart16550_input_close,
745 	.trigger =	snd_uart16550_input_trigger,
746 };
747 
748 static int snd_uart16550_free(snd_uart16550_t *uart)
749 {
750 	if (uart->irq >= 0)
751 		free_irq(uart->irq, (void *)uart);
752 	if (uart->res_base) {
753 		release_resource(uart->res_base);
754 		kfree_nocheck(uart->res_base);
755 	}
756 	kfree(uart);
757 	return 0;
758 };
759 
760 static int snd_uart16550_dev_free(snd_device_t *device)
761 {
762 	snd_uart16550_t *uart = device->device_data;
763 	return snd_uart16550_free(uart);
764 }
765 
766 static int __init snd_uart16550_create(snd_card_t * card,
767 				       unsigned long iobase,
768 				       int irq,
769 				       unsigned int speed,
770 				       unsigned int base,
771 				       int adaptor,
772 				       int droponfull,
773 				       snd_uart16550_t **ruart)
774 {
775 	static snd_device_ops_t ops = {
776 		.dev_free =	snd_uart16550_dev_free,
777 	};
778 	snd_uart16550_t *uart;
779 	int err;
780 
781 
782 	if ((uart = kcalloc(1, sizeof(*uart), GFP_KERNEL)) == NULL)
783 		return -ENOMEM;
784 	uart->adaptor = adaptor;
785 	uart->card = card;
786 	spin_lock_init(&uart->open_lock);
787 	uart->irq = -1;
788 	uart->base = iobase;
789 	uart->drop_on_full = droponfull;
790 
791 	if ((err = snd_uart16550_detect(uart)) <= 0) {
792 		printk(KERN_ERR "no UART detected at 0x%lx\n", iobase);
793 		return err;
794 	}
795 
796 	if (irq >= 0 && irq != SNDRV_AUTO_IRQ) {
797 		if (request_irq(irq, snd_uart16550_interrupt,
798 				SA_INTERRUPT, "Serial MIDI", (void *) uart)) {
799 			snd_printk("irq %d busy. Using Polling.\n", irq);
800 		} else {
801 			uart->irq = irq;
802 		}
803 	}
804 	uart->divisor = base / speed;
805 	uart->speed = base / (unsigned int)uart->divisor;
806 	uart->speed_base = base;
807 	uart->prev_out = -1;
808 	uart->prev_in = 0;
809 	uart->rstatus = 0;
810 	memset(uart->prev_status, 0x80, sizeof(unsigned char) * SNDRV_SERIAL_MAX_OUTS);
811 	init_timer(&uart->buffer_timer);
812 	uart->buffer_timer.function = snd_uart16550_buffer_timer;
813 	uart->buffer_timer.data = (unsigned long)uart;
814 	uart->timer_running = 0;
815 
816 	/* Register device */
817 	if ((err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, uart, &ops)) < 0) {
818 		snd_uart16550_free(uart);
819 		return err;
820 	}
821 
822 	switch (uart->adaptor) {
823 	case SNDRV_SERIAL_MS124W_SA:
824 	case SNDRV_SERIAL_MS124W_MB:
825 		/* MS-124W can draw power from RTS and DTR if they
826 		   are in opposite states. */
827 		outb(UART_MCR_RTS | (0&UART_MCR_DTR), uart->base + UART_MCR);
828 		break;
829 	case SNDRV_SERIAL_MS124T:
830 		/* MS-124T can draw power from RTS and/or DTR (preferably
831 		   both) if they are asserted. */
832 		outb(UART_MCR_RTS | UART_MCR_DTR, uart->base + UART_MCR);
833 		break;
834 	default:
835 		break;
836 	}
837 
838 	if (ruart)
839 		*ruart = uart;
840 
841 	return 0;
842 }
843 
844 static void __init snd_uart16550_substreams(snd_rawmidi_str_t *stream)
845 {
846 	struct list_head *list;
847 
848 	list_for_each(list, &stream->substreams) {
849 		snd_rawmidi_substream_t *substream = list_entry(list, snd_rawmidi_substream_t, list);
850 		sprintf(substream->name, "Serial MIDI %d", substream->number + 1);
851 	}
852 }
853 
854 static int __init snd_uart16550_rmidi(snd_uart16550_t *uart, int device, int outs, int ins, snd_rawmidi_t **rmidi)
855 {
856 	snd_rawmidi_t *rrawmidi;
857 	int err;
858 
859 	if ((err = snd_rawmidi_new(uart->card, "UART Serial MIDI", device, outs, ins, &rrawmidi)) < 0)
860 		return err;
861 	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_INPUT, &snd_uart16550_input);
862 	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &snd_uart16550_output);
863 	strcpy(rrawmidi->name, "Serial MIDI");
864 	snd_uart16550_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT]);
865 	snd_uart16550_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_INPUT]);
866 	rrawmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
867 			       SNDRV_RAWMIDI_INFO_INPUT |
868 			       SNDRV_RAWMIDI_INFO_DUPLEX;
869 	rrawmidi->private_data = uart;
870 	if (rmidi)
871 		*rmidi = rrawmidi;
872 	return 0;
873 }
874 
875 static int __init snd_serial_probe(int dev)
876 {
877 	snd_card_t *card;
878 	snd_uart16550_t *uart;
879 	int err;
880 
881 	if (!enable[dev])
882 		return -ENOENT;
883 
884 	switch (adaptor[dev]) {
885 	case SNDRV_SERIAL_SOUNDCANVAS:
886 		ins[dev] = 1;
887 		break;
888 	case SNDRV_SERIAL_MS124T:
889 	case SNDRV_SERIAL_MS124W_SA:
890 		outs[dev] = 1;
891 		ins[dev] = 1;
892 		break;
893 	case SNDRV_SERIAL_MS124W_MB:
894 		outs[dev] = 16;
895 		ins[dev] = 1;
896 		break;
897 	case SNDRV_SERIAL_GENERIC:
898 		break;
899 	default:
900 		snd_printk("Adaptor type is out of range 0-%d (%d)\n",
901 			   SNDRV_SERIAL_MAX_ADAPTOR, adaptor[dev]);
902 		return -ENODEV;
903 	}
904 
905 	if (outs[dev] < 1 || outs[dev] > SNDRV_SERIAL_MAX_OUTS) {
906 		snd_printk("Count of outputs is out of range 1-%d (%d)\n",
907 			   SNDRV_SERIAL_MAX_OUTS, outs[dev]);
908 		return -ENODEV;
909 	}
910 
911 	if (ins[dev] < 1 || ins[dev] > SNDRV_SERIAL_MAX_INS) {
912 		snd_printk("Count of inputs is out of range 1-%d (%d)\n",
913 			   SNDRV_SERIAL_MAX_INS, ins[dev]);
914 		return -ENODEV;
915 	}
916 
917 	card  = snd_card_new(index[dev], id[dev], THIS_MODULE, 0);
918 	if (card == NULL)
919 		return -ENOMEM;
920 
921 	strcpy(card->driver, "Serial");
922 	strcpy(card->shortname, "Serial MIDI (UART16550A)");
923 
924 	if ((err = snd_uart16550_create(card,
925 					port[dev],
926 					irq[dev],
927 					speed[dev],
928 					base[dev],
929 					adaptor[dev],
930 					droponfull[dev],
931 					&uart)) < 0) {
932 		snd_card_free(card);
933 		return err;
934 	}
935 
936 	if ((err = snd_uart16550_rmidi(uart, 0, outs[dev], ins[dev], &uart->rmidi)) < 0) {
937 		snd_card_free(card);
938 		return err;
939 	}
940 
941 	sprintf(card->longname, "%s at 0x%lx, irq %d speed %d div %d outs %d ins %d adaptor %s droponfull %d",
942 		card->shortname,
943 		uart->base,
944 		uart->irq,
945 		uart->speed,
946 		(int)uart->divisor,
947 		outs[dev],
948 		ins[dev],
949 		adaptor_names[uart->adaptor],
950 		uart->drop_on_full);
951 
952 	if ((err = snd_card_register(card)) < 0) {
953 		snd_card_free(card);
954 		return err;
955 	}
956 	snd_serial_cards[dev] = card;
957 	return 0;
958 }
959 
960 static int __init alsa_card_serial_init(void)
961 {
962 	int dev = 0;
963 	int cards = 0;
964 
965 	for (dev = 0; dev < SNDRV_CARDS; dev++) {
966 		if (snd_serial_probe(dev) == 0)
967 			cards++;
968 	}
969 
970 	if (cards == 0) {
971 #ifdef MODULE
972 		printk(KERN_ERR "serial midi soundcard not found or device busy\n");
973 #endif
974 		return -ENODEV;
975 	}
976 	return 0;
977 }
978 
979 static void __exit alsa_card_serial_exit(void)
980 {
981 	int dev;
982 
983 	for (dev = 0; dev < SNDRV_CARDS; dev++) {
984 		if (snd_serial_cards[dev] != NULL)
985 			snd_card_free(snd_serial_cards[dev]);
986 	}
987 }
988 
989 module_init(alsa_card_serial_init)
990 module_exit(alsa_card_serial_exit)
991